Plasmas are gaseous discharges widely used to modify the surface properties of materials. Plasma-based surface processes, such as etching and deposition of thin films, are vitally important to the manufacturing of integrated circuits (ICs) in the electronics industry. Typical plasmas (also known as “glow discharges”) are formed by ionizing a gas between solid electrodes using either radio-frequency (rf) or direct current (dc) power.
While most industrial applications employ plasmas for chemical modification of solid surfaces, there have been a small number of experiments dating back to more than a hundred years ago in which the use of low-pressure plasmas was investigated for gas-liquid interactions. Applications of this technology, know as glow discharge electrolysis, remain elusive, however, because stable discharge operation of the plasma requires a vacuum environment, which restricts potential electrolytes to those with extremely low vapor pressures, such as ionic liquids or solid oxides.